文章基本信息

标题：PHOTOMETRIC STUDIES OF THREE NEGLECTED SHORT-PERIOD CONTACT BINARIES GN BOOTIS, BL LEONIS, AND V1918 CYGNI
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作者：Y.-G. Yang ; S.-B. Qian ; H.-F. Dai 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2013
卷号：145
期号：3
DOI：10.1088/0004-6256/145/3/60
语种：English
出版社：American Institute of Physics
摘要：We present new photometry for three short-period contact binaries, GN Boo, BL Leo, and V1918 Cyg, observed from 2008 December to 2012 April using several small telescopes in China. Photometric models were deduced from new observations using the updated Wilson-Devinney Code. The results show that GN Boo and BL Leo are W-type contact binaries, while V1918 Cyg is an A-type one. The mass ratios and fill-out factors are q = 0.320(± 0.002) and f = 5.8(± 0.1)% for GN Boo, q = 0.476(± 0.005) and f = 21.3(± 1.1)% for BL Leo, q = 0.264(± 0.002), and f = 49.7(± 0.7)% for V1918 Cyg, respectively. From the (O – C) curves, it is discovered that the orbital periods of three binaries have varied in a complicated way, i.e., cyclic oscillation for GN Boo, long-term period decrease for BL Leo, and both for V1918 Cyg. The cyclic variations for GN Boo and V1918 Cyg may probably be attributed to the magnetic activity of the primary component or light-time effect due to the third body. Meanwhile, the secular period decreases for BL Leo and V1918 Cyg may result from mass transfer from the primary to the secondary, accompanying the mass and angular momentum loss from the central system. Finally, GN Boo, BL Leo, and V1918 Cyg will evolve into deep contact binaries. Additionally, a statistical study of 37 contact binaries with decreasing periods is given. We obtained the relations of q – f and q – dln P/dt, and preliminarily determined the mass loss rate of dln M/dt from the binary system.
关键词：binaries: close;binaries: eclipsing;stars: individual (GN Boo; BL Leo; V1918 Cyg) Online-only material: machine-readable and VO tables